1// run
2
3//go:build !js && !wasip1
4
5// Copyright 2022 The Go Authors. All rights reserved.
6// Use of this source code is governed by a BSD-style
7// license that can be found in the LICENSE file.
8
9// Issue 52127: Too many syntax errors in many files can
10// cause deadlocks instead of displaying error messages
11// correctly.
12
13package main
14
15import (
16	"bytes"
17	"fmt"
18	"os"
19	"os/exec"
20	"path/filepath"
21)
22
23func main() {
24	dir, err := os.MkdirTemp("", "issue52127")
25	if err != nil {
26		panic(err)
27	}
28	defer os.RemoveAll(dir)
29
30	args := []string{"go", "build"}
31	write := func(prefix string, i int, data string) {
32		filename := filepath.Join(dir, fmt.Sprintf("%s%d.go", prefix, i))
33		if err := os.WriteFile(filename, []byte(data), 0o644); err != nil {
34			panic(err)
35		}
36		args = append(args, filename)
37	}
38
39	for i := 0; i < 100; i++ {
40		write("a", i, `package p
41`)
42	}
43	for i := 0; i < 100; i++ {
44		write("b", i, `package p
45var
46var
47var
48var
49var
50`)
51	}
52
53	cmd := exec.Command(args[0], args[1:]...)
54	output, err := cmd.CombinedOutput()
55	if err == nil {
56		panic("compile succeeded unexpectedly")
57	}
58	if !bytes.Contains(output, []byte("syntax error:")) {
59		panic(fmt.Sprintf(`missing "syntax error" in compiler output; got:
60%s`, output))
61	}
62}